The use of renewable energy technologies, such as wind and solar energy, is vastly increasing. With their increasing use, their incorporation into power grids is essential for taking advantage of the energy they produce. The incorporation of these technologies into these grids requires the use of devices that turn direct current into alternating current called power inverters. Because of the high demand for power and the growing capacity for these renewable energy technologies to supply this demand, power electronic devices need to be able to handle this increased demand.
Currently, power inverters are used in parallel (e.g., connected such that electrical current flows through all inverters simultaneous) to accommodate the high power/current demand for electrical energy in power grids. When inverters are used in parallel to allow parallel power generation, such a configuration is often referred to as load sharing or power sharing. Droop control is a control strategy commonly applied to power generators to allow load sharing. This strategy allows for equal load balancing between inverters, but requires that output impedances be matched between the inverters. This results in inaccurate reactive power sharing—an important aspect of power sharing performance. Traditional droop control strategies are also unable to handle system disturbances, such as large or quick load changes, variations in output impedances, and fluctuating DC-link voltages.